As is well known in the art, many building codes require electrical wiring to be enclosed in electrical conduits which may be connected to each other in a branch network through the use of junctions such as electrical conduit bodies or elbows. Such electrical conduit systems are required to safely provide electric power to homes, commercial buildings, and the like. These conduit systems often include long runs of rigid electrical conduits with frequent changes in direction, such as 90 degree turns, and interruptions with various couplings to accommodate bends or changes in direction. The conduits themselves serve to provide a protective housing for the wires therein and to route these wires throughout the building or other installation as required. Conduits or elbows are typically constructed of a rigid metal pipe.
Typical electrical conduit bodies are often installed in the conduit systems at various locations to provide accesses to the wires in the conduits, or to route the wires through a bulkhead, an electrical equipment enclosure, a junction box, or other electrical fixture. These are marketed, for example, by Thomas and Betts Corporation, of Memphis, Tenn., in conjunction with the trademark “THOMAS & BETTS”.
These electrical conduit bodies have a generally oblong body provided with integral longitudinal walls and end walls and a side wall, such walls defining a chamber open on one side of the body. Conventional conduit bodies can have openings at one or more ends as well as through the upper and lower walls. For instance, a removable cover may be provided for closing the open side of the body. The body is also provided with spaced conduit connecting hubs each defining a passageway communicating with the chamber defined by the body. The spacious accessible wiring chamber provides for a convenient location to pull conductors and make splices as well as provide a weather resistant conduit system when used with covers and gaskets.
Typically, wires are inserted through an opening on the bottom or side of the conduit body and out through another opening located along another side or top of the conduit body. Most often, the inside surface of these conduits is metal, some conduits having a surface rougher than others. The friction caused by rubbing of the wires against the edges of the hub access port of the conduit body makes it difficult to pull the wire through the conduit housing, especially if there are many bends along the conduit length. While power pullers are used for this purpose, it is not unusual for the puller cords to break, leaving a partially pulled wire end that is very difficult to access within the conduit. In addition, the friction of the wire insulation rubbing against the edges of openings of the conduit body may damage the insulation on the wires.
Attempts to minimize such friction associated with the rubbing of wires against the openings of conduit bodies at the manufacturer's end have been less than satisfactory. For instance, some manufacturers have inserted roller pins and smooth clip shields to minimize the friction. Other attempts to minimize such friction have also been utilized, but they do not satisfactorily address the problem.